Johnson's personality is randomized when Veronaville is loaded. The following personality is only referenced in the game files. This happens with all headmasters. According to his SimDNA in SimPE, his hair was blond before it turned grey. Sometimes if Johnson is made playable, his PlumbBob will be inside him, instead of above his head. This happens with several other NPCs in The Sims 2.

↑All headmasters that look like elders have fewer days than the standard 29 before aging up. This is probably because their character data matches that of a typical elder Sim - 54 days in previous lifespans, and having between 10 and 20 days left in their lifespan, etc. This can be proven through SimPE.